Power shovel



July 1 1969 T. LEARMONT 3,452,890

POWER SHOVEL Filed Aug. 25, 1967 sheet 1 o f 4 INVENTOR TOM LEARMONT ATTORNEY July 1, 1969 T, L EARMONT 3,452,890

POWER SHOVEL Filed Aug. 25, 1967 sheet of 4 INVENTOR TOM LEARMONT ATTORNEY* T. LEARMONT POWER SHOVEL July 1, 1969 Sheet i of 4 Filed Aug. 25, 1967 INVENTOF TOM LEARMONT BY- i,

'ATTORNEY T. LEARMONT July 1., 1969 POWER SHOVEL Sheet Filed Aug. 25, 1967 INVENTOR TOM LEARMONT ATTORNEY Unted States Patent O U.S. Cl. 214-138 12 Claims ABSTRACT F THE DISCLOSURE The revolving frame of a quarry shovel supports a boom pivotally mounted on its front end and an A-frame. A bucket handle with a bucket on its lower end is pivoted intermediate its ends to the top of the boom. A hoist cable extends from a drum on the revolving frame over a sheave on the A-frame to act on the top of the bucket handle. A cable driven crowd handle riding on top of the A-frame has its front end fastened to a crank projecting posteriorly from the bucket handle.

Background of the invention The present invention was created as an improvement on a new type of front end for a power shovel that can be used in sizes ranging from relatively small excavators to huge strip mining machines. The new type of front end, which is the subject of co-pending application of Ellis C. Wilson for a Power Shovel Apparatus Ser. No. 659,970 filed on Aug. 11, 1967 and owned by the same assignee as this application, employs a shortened boom with a bucket handle pivoted on the end of the boom, and a mast which is pivotally mounted to rise from the end of the boom. The top of -the mast is connected to the outer end of the bucket handle, and it is also connected to the hoist cables which pass over hoist sheaves in the top of the A-frame and down to cable drums on the revolving frame. Crowd force is applied through a crowd handle which rides upon and is driven from the A-frame and which has its anterior end fastened to the top of the boom.

The present invention dilfers from the structure of the mentioned co-pending application in several respects. Most notable of the differences is the elimination by the present invention of the mast and the mounting of the bucket handle intermediate its ends on the boom. Hence, the hoist force is applied to the top of the bucket handle, pivoting it around its mounting on the boom. With such a structure, a crowd handle acting directly on the pivotal mounting of the bucket handle on the boom will manifest undesirable characteristics: when the boom angle is high the crowd force at the bucket is at its minimum but if the angle of the boom is lowered the dumping height at maximum reach is undesirably reduced. It was discovered that these deficiencies can be overcome by olf-setting the connection of the crowd handle to the bucket handle posteriorly of the pivotal mounting of the bucket handle on the boom.

Recent prior art devices designed to perform similar excavating operations as machines embodying the present invention are shown in U.S. Patents Nos. 2,660,816, 2,753,060, 2,775,356, 2,804,701, 2,965,253, 3,080,076, 3,120,315, 3,129,832 3,166,205, 3,189,203, 3,207,340, 3,239,083, 3,259,259 and 3,291,328. Unlike the structures taught in those patents, however, the present invention employs a crowd mechanism acting on a point intermediate the ends of the bucket handle. This structure obviates the need for, and thus the limitations of, hydraulic crowd cylinders mounted between the boom or the revolving frame and the bucket handle. Also, instead `of acting on the pivotal junction between the boom and the bucket ice handle, the present invention as is mentioned above, would off-set the connection of the crowd handle of the bucket handle from the pivotal junction of the boom and the bucket handle. The present invention thereby achieves maximum crowd force at ground level immediately in front of the machine, and maximum dumping height at maximum crowd reach.

Summary of the invention The present invention relates to an excavator apparatus, and more specifically it resides in the combination of a boom pivotally mounted at one end to a main frame, a crowd support frame that is mounted behind the boom on the main frame, a bucket handle Which is pivotally mounted intermediate its ends to said boom, a hoist cable which acts on the top of the bucket handle, and a crowd handle that is supported from the crowd support frame and connected to the bucket handle at a point olf-set posteriorly from the bucket handle.

The combination set forth above provides a power shovel which manifests increased payload capacity, shorter cycling time, and greater versatility, llexibility and efficiency than was hitherto possible. The use of a crowd handle supported and driven from the A-frame provides large crowd forces with a long reach, and makes the invention applicable to power shovels of all sizes. Also, the combination of the struc-tures mentioned with a pivotable bucket instead of the conventional dipper makes the structure lighter, increases digging versatility and reduces maintenance requirements. The excavator that embodies `the present invention is also lighter weight, better balanced and less subject to maintenance problems than its predecessors in the art.

Brief description of the drawings FIGS. 1 through 4 of the drawings illustrate in side elevation a quarry shovel embodying the present invention showing the relationship `of Ithe moving members when the bucket is in various operating positions.

Description of the preferred embodiment The quarry shovel shown in the drawings has a revolving frame 1 as a main supporting frame for the front end, or digging mechanism. The revolving frame 1 is rotatably mounted on a running gear 2, which includes a crawler tread 3 for propelling the excavator and a swing mechanism 4 for rotating the revolving frame 1. A cab 5 is mounted on the revolving frame 1 to house the engines which provide the power for the excavator, and to enclose the operator. An A-frame 6, which is made up of a pair of parallel front legs 7 and back legs 8 joined together at the top stands near the center of the revolving frame 1, so that its weight is located over the running gear 2. Immediately in front of the front legs 7 of the A- frame 6, a boom 9 which is made up of two side by side members fastened together by cross bracing, has its inner end pivotally mounted in conventional fashion on the revolving frame 1.

A bucket handle 10 is pivotally mounted intermediate its top end and its bottom end to the outer end of the boom 9 at a hinge joint 11, at a projection 12 on the' posterior side of the bucket handle 10. A crank 13 is built on thebucket handle 10 at the hinge projection 12 to extend posteriorly from the bucket handle 10 beyond the hinge projection 12. The crank 13 has a crowd bearing 14 at its outer end, which is thereby posteriorly olf-set from the pivotal mounting of the bucket handle 10 on the top of the boom 9. Hoist pulleys 15 are mounted in the top of the bucket handle 10 and a scoop bucket 16 is pivotally mounted to the bottom end of the bucket handle 10. Hence the boom 9 and the bucket handle 10 joined by the hinge joint 11 may be considered an articulated arm for supporting and controlling the bucket 16.

Since the scoop bucket 16 is pivotally mounted to the bottom end of the bucket handle 10, a tilt mechanism 17, which is a separate invention, is required to control the attitude of the scoop bucket 16 about its pivotal mounting 18. The tilt mechanism 17 is powered by a pair of end mounted hydraulic cylinders 19 and 20 which have blind ends 21 and 22 pivotally fastened to the bucket handle and piston rod ends 23 and 24 pivotally mounted to a compound lever 25 on opposite sides of the fulcrum shaft 26 about which the compound lever 25 is journaled on the bucket handle 10. A link 27 joins the posterior end of the compound lever 25 to a second class lever 28, one end of which is journaled about a fulcrum shaft 29 journaled in the bucket handle 10 just above the pivotal mounting 18 of the scoop bucket 16, and the other end of the second class lever 28 is joined by a link 30 to the top side of the scoop bucket 16 intermediate the pivotal mounting 18 of the scoop bucket 16 and the mouth 31 of the scoop bucket 16. A suitable hydraulic power unit (not shown) is provided to control and drive the hydraulic cylinders 19 and 20 of the scoop bucket tilt mechanism 17 so as to control the attitude of the scoop bucket 16. The lower edge of the mouth 31 of the scoop bucket 16 is provided with digging teeth 32.

A crowd mechanism crowds the bucket 16 horizontally by tending to straighten the articulated bucket supporting arm, or in other words, to widen the angle between the boom 9 and the lower portion of the bucket handle. The crowd mechanism includes a crowd handle 33 which is supported on rollers 34 mounted on top of the A- frame 6, and which has its front end pivotally fastened to the crank 13 by a shaft 35 journaled in the crowd bearing 14 on the end of the crank 13 on the bucket handle 10. Front and back crowd stops 36 and 37, respectively, project downwardly from the crowd handle 33 to limit the reciprocating travel of the crowd handle 33. A rope crowd drive shown in the co-pending application Ser. No. 593,932 tiled on Nov. 14, 1966, entitled A Rope Crowd for a Knee Action Shovel assigned to the same assignee as the present application, is employed in this embodiment and reference may be had to that application for the details of the structure of that crowd mechanism. Of course, other types of crowd drives may be used such as an hydraulic crowd, a rack and pinion crowd, or an electric crowd, or the like. For present purposes, it may be noted that there is a crowd sheave means 38 mounted on the back end of the crowd handle 33 and a crowd sheave means 39 mounted in a sliding block 40 toward the front end of the crowd handle 33. A crowd cable 41 passes about both sheaves 38 and 39, over crowd pulleys (not shown) mounted on the top of the A-frame 6 and down to a power driven crowd cable drum 42 mounted on the revolving frame 1. A pair of low pressure hydraulic cylinders 43 and 44 are endmounted above and beneath the crowd handle 33, respectively, between brackets 45 and 46 on the crowd handle 33 and brackets 47 and 48 on the sliding block 40 to take up slack in the crowd cable 41. The hydraulic cylinders 43 and 44 are under continuous low pressure through check valves (not shown) urging the sliding block 40 outwardly, so that if any slack develops in the crowd cable 41 it will be taken up. When pressure is exerted against the sliding block 40 by the crowd cable 41, the check valves (not shown) hold the cylinders 43 and 44 and prevent the sliding block 40 from moving rearwardly.

A hoist mechanism pivots the bucket handle 10 about its hinge joint 11 on the boom 9 to impart a vertical component to the movement of the bucket 16.

Hoist sheaves 49 are mounted in the top of the A- frame 6 and a pulley 50 is lixed to the front leg members 7 of the A-frame 6. A hoist cable 51 extends from a power driven hoist cable drum 52 mounted on the revolving frame 1 over the hoist sheaves 49 in the top of the A-frame 6, about the hoist pulleys 15 mounted in the top of the bucket handle 10 and about the iixed pulley 50 mounted on the front leg 7 of the A-frame 6. Although reference is made here to a hoist mechanism or hoist means comprising the structure just described and a crowd mechanism also described above, it will be understood that the hoist and crowd functions are not as clearly defined in a mechanism embodying the present invention as in the conventional excavator where this terminology originated. Hence, under some circumstances actuation of the hoist mechanism may crowd the bucket 16, and under some circumstances movement of the crowd handle 33 may hoist the bucket 16. Nevertheless, in most circumstances, the described crowd mechanism will effect a crowd motion and the described hoist mechanism will effect a hoist motion of the scoop bucket 16.

FIGS. 1, 3, and 4 viewed in succession show three positions in a typical cycle of operation. In FIG. 1, the bucket 16 is near the beginning of its horizontal crowd action at the level of the surface on which the power shovel is resting. In FIG. 3, the bucket 16 is located toward the end of that horizontal crowd movement, and in FIG. 4 the bucket 16 is raised to its maximum height and reach for dumping. The relatively low angle of the boom 9 in FIGS. 1 and 3 as compared with the high angle of the boom 9 in FIG. 4 demonstrates the prominent advantages of the present invention. The low angle of the boom 9 during the horizontal crowding movement insures maximum crowd force at the teeth 32 at the bucket 16 relative to the crowd force actually applied by the crowd handle 33 as it advances to crank the bucket handle 10 about its pivotal mounting 11 on the end of the Iboom 9. The high angle of the -boom 9 in FIG. 4 provides the extraordinary dumping height and reach of a power shovel embodying the present invention.

The extreme positions of the crowd handle 33 are illustrated in FIGS. 2, 3 and 4. In FIG. 2 the crowd handle 33 is retracted almost to the point where the front stop 36 abuts the rollers 34 on the top of the A-frame 6, and in FIGS. 3 and 4 the back stop 37 on the crowd handle 33 is resting on the back of the rollers 34. FIG. l illustrates an intermediate position of the crowd handle 33, although it is closer to its extended position. FIG. l shows the hoist cable 51 almost fully extended. FIGS. 2 and 3 illustrate the hoist cable 51 somewhat retracted, and a comparison of the positions of the bucket for the same hoist cable lengths is noteworthy. In FIG. 4, the hoist cable 51 is completely retracted.

In addition to illustrating the operating positions and relationships of the moving parts of the embodiment illustrated here, the drawings also illustrate the relative dimensions and shapes of the various members. It is evident in FIG. 2 that the length of the boom 9 is approximately equal to the distance from the hoinge joint 11 of the bucket handle 10 on the boom 9 to the pivotal mounting 18 of the bucket 16 on the bottom end of the bucket handle 10. In a commercial embodiment of the invention, the boom 9 will be approximately 2l feet 10 inches long, with that portion of the bucket handle 10 from the hinge joint 11 to its top end being approximately 13 feet long. In FIG. 3, the crank 13 is aligned with the boom 9, from which relationship may be discerned that the crank 13 is approximately one seventh as long as the boom 9, and thus approximately a seventh the distance from the pivotal mounting 11 of the bucket handle 10 to the pivotal mounting 18 of the bucket 16, which is mounted on the end of the bucket handle 10.

In the commercial embodiment referred to above, the crank 13 is approximately 3 feet long and lines drawn from the pivotal mounting 14 of the crowd handle 33 to the crank 13 and from the pivotal mounting 18 and the bucket 16 to the pivotal mounting 11 of the bucket handle 10 on the boom 9 will intesect to form a right angle. In that commercial embodiment the use of the crank 13, which permits the pivotal mounting 14 of the crowd handle 33 to the bucket handle 10 to be posteriorly cfr"- set from the pivotal mounting 11 of the bucket handle 10 to the boom 9, allows 30 percent higher cutting height at maximum crowd reach than would be possible if there were no off-set. With the crank, the commercial embodiment of the invention achieves a cutting height of 371/2 feet at a reach of 451/3 feet, whereas without the crank the same commercial embodiment would have a maximum cutting height of only 29 feet and a maximum reach of 481/3 feet. Also, at a 26 foot cutting height, the present invention provides percent greater digging force with 37 percent less crowd force than with the same machine without benefit of the crank 13, which provides the off-set of the pivotal connections 14 and 11.

It is believed that the substantial advantages of the invention can be achieved so long as the above described angle of the crank 13 to the bucket handle 10 is between 70 and 90 degrees so that the minimum angle of the boom 9 to the horizontal when the bucket 16 is at maximum level for position is approximately -30 degrees. The length of the crank is also important and it should lie within the range of one fifth to one eighth the length of the boom 9, or the substantially equal distance between the hinge joint 11 of the bucket handle 10 to the boom 9 and the pivotal mounting 18 of the bucket 16. Maintaining the length of the crank 13 within that range, a maximum angle of the boom 9 to the horizontal with the crowd extended, consistent with achieving maximum dumping height and optimum distribution of forces in that position, would be approximately 40-45 degrees.

The structure of the invention described achieves the stated advantages over the previously mentioned copending application owned by the same assignee as the present invention of Wilson for a Power Shovel Apparatus, Ser. No. 659,970 filed Aug. ll, 1967. Relative to the other known prior arts, also mentioned above, a power shovel embodying the present invention will also enjoy the advantages set forth in that co-pending application. The essence of this invention, as distinguished from any particular embodiment participating in that essence, including the embodiment disclosed above, is set forth in the claims that follow, and the details of the disclosed embodiment set forth above are intended, not to define the invention, but rather to show those skilled in the art the best mode contemplated for practicing this invention.

I claim:

1. A power shovel apparatus comprising the combination of a main supporting frame having a crowd frame mounted on it;

an articulated bucket arm including a boom and a bucket handle fastened together at a hinge joint, said boom having an inner end pivotally mounted on said main supporting frame in front of said crowd frame; and a crowd mechanism including a crowd handle reciprocably supported on said crowd frame, said crowd handle having a front end connected to said bucket handle at a location olf-set posteriorly from said hinge joint and having a crowd drive to reciprocate said crowd handle to crank said bucket handle about said hinge joint.

2. A power shovel apparatus as set forth in claim 1 wherein said hinge joint lies intermediate a top end and a bottom end of said bucket handle;

and a hoist mechanism acts between said crowd frame and said top end of said bucket handle to pivot said bucket handle about said hinge joint.

3. A power shovel apparatus as set forth in claim 2 wherein said hoist mechanism includes a cable driven by a cable drum on said main supporting frame and passing over sheaves mounted on said crowd frame and connected to said top end of said bucket handle.

4. A power shovel apparatus as set forth in claim 1 wherein said crowd support frame is an A-frame; and said crowd mechanism includes a crowd drive operatively connected to said A-frame and said crowd handle to cause said crowd handle to reciprocate on its mounting. 5. A power shovel apparatus as set forth in claim 4 wherein said joint lies intermediate a top end and a Ibottom end of said bucket handle;

a hoist cable having an end fastened to a power driven cable drum mounted on said main supporting frame passes over a sheave mounted on the top of said A-frame and is connected to said top end of said bucket handle to pivot said bucket handle about said joint. 6. A power shovel apparatus as set forth in claim 5 wherein a bucket is pivotally mounted on said bottom end of said bucket handle; and a bucket tilt mechanism acting between said bucket handle and said bucket controls the attitude of said bucket. 7. A power shovel apparatus as set forth in claim 4 wherein said crowd drive is a rope drive having a power driven cable drum mounted on said main supporting frame and a cable driven by said cable drum and passing over crowd sheaves mounted in the top of said A-frame to act on said crowd handle. 8. A power shovel as set forth in claim 7 wherein said main supporting frame is a revolving frame mounted on a running gear. 9. A power shovel apparatus as set forth in claim 6 wherein said boom is never less than 25 from horizontal and never more than 45 from horizontal during its operating cycle.

f10. Excavator apparatus comprising the combination o a main supporting frame;

a boom having a bottom end pivotally mounted on said main supporting frame to swing in a vertical arc;

an A-frame mounted on said main supporting frame behind said boom and having a hoist sheave mounted on its top end supporting a crowd mechanism;

a bucket handle having a top end, a bottom end, a boom pivot intermediate said ends for pivotally mounting said bucket handle on said boom and a crowd pivot spaced rearwardly from said boom pivot; v

and a crowd handle supported by said crowd mechanism on said A-frame and co-operating with said crowd mechanism for reciprocating longitudinal movement, and having a front end pivotally fastened to said crowd pivot of said boom handle.

11. Excavator apparatus as set forth in claim 10 wherein a bucket is pivotally mounted on said bottom end of said bucket handle;

and a bucket tilt mechanism is fastened to said bucket to control the attitude of said bucket about its pivotal mounting on said bucket handle.

12. A power shovel apparatus comprising the combination of a main supporting frame;

a boom having an inner end pivotally mounted on said supporting frame and an outer end projecting outwardly from said main supporting frame;

a bucket handle pivotally mounted on said boom near said outer end and having a crank projecting poste- 7 8 rorly from where said bucket handle is mounted on References Cited a lvdorlxll. ort ramevmounted osteriorl of said UNITED STATES PATENTS boom. pp p y 3,080,076 3/1963 Randall 214-138 3,148,789 9/1964 Gourjon 214-138 and a crowd means acting between said crowd support r frame and said crank to pivot said bucket handle 0 aboutits mounting on said boom HUGO O. SCHULZ, Primary Examiner. 

